Then I entered my office yesterday and had to notice my office-mate Jimmy has vanished, apparently he moved into another office. Well, effectively this means I have managed to upgrade myself from a non-window desk in a shared office to a window desk in an office of my own. Now the only thing that's missing is a couch.

Today we had a water outage in the building, and were asked not to use the bathrooms. The plumber arrived and we soon received an email saying 'the water problem has now been corrected and there is now water in the building'. A friend remarked about this 'water in the building doesn't sound too good either'.

I am very happy to report that my workshop 'Experimental Search for Quantum Gravity' has been approved, and will take place here at PI from Nov 5th to 9th. Bianca, Achim and Tomasz are helping with the organization. We even have a website, but so far there is about no information on it.

Besides this, my landlord wants to increase the rent, and I decided I will move out. Actually not because of the rent increase, but because I find it kind of weird that rain leaks through the ceiling even though I don't live under the roof.

Okay, but besides all this I have to announce that I will be travelling the next weeks, starting from tomorrow morning. So you are facing a slow time on this blog. I can feed you with photos from Europe but probably wont have the time to write anything substantial for quite a while.

Think for a moment about the people in your workplace. Have you ever considered that one of your coworkers might forever revolutionize our understanding of the universe, bending space and time in his or her mind?

Have I ever considered that my coworkers aim to revolutionize our understanding of the universe? *yawn* Who doesn't?

Well, on the HiRISE web page it is described innocuously as "Candidate Cavern Entrance Northeast of Arsia Mons" - and that's what it is supposed to be: a round hole with a diameter of about 100 meter in the ceiling of a wide cavern in the Martian ground. It's so deep that the sun, at 03:27 PM local Martian time at about 38 degrees above the horizon, doesn't reach the ground. You should have a look at this detailed photo...

Similar geological features (even with about the same diameter) exist also on Earth - for example the Zacaton sinkholes in Mexico. On Earth, these caverns are filled with water (see here for a detailed description as PDF file). The satellite images from the hole on Mars are now better than those of Zacaton at google.maps - that's crazy...

UPDATE (September 7, 2007):New photos, also taken by the HiRISE collaboration, show the shadow of the rim cast onto the wall of the pit. The photo allows to calculate that the pit is at least 78 meters (255 feet) deep, and the new data suggest that the hole has volcanic origins.

Friday, May 25, 2007

Yesterday, I was stuck on a six lane highway. I mean six lanes in each direction, somewhere in LA, cars bumper to bumper, people sweating and cursing and tapping fingers on their rooftops in the Californian afternoon heat. Picture this, and then tell me how you can not conclude that the extinction of the human race must be near. But I have always had my problems with the doomsday argument.

One ingredient is the Copernican principle, which states that you should not expect to be special in any regard: our galaxy is not the center of the universe, the earth is not the center of the Milky Way, and Waterloo is not in the middle of nowhere. A typical example is the number of planets in our solar system. The Copernican principle tells you that we are an average solar system in an average galaxy, and the number of planets is not exceptional but rather common. You then expect other solar systems to have a similar number of planets.

It is quite natural for human beings to adopt the Copernican principle. Typically, we assume everybody else experiences the world similar as we do. Needless to say, this is the cause of countless problems, and the reason why the men in my life state frequently they don't understand me... ah, sorry, getting distracted...

To briefly summarize the doomsday argument: consider the lives of humans as distributed over time, until doomsday, after which there are no humans any more. Then the Copernican principle comes into play. Neither you nor me is special in any regard, and the conclusion is that with equal probability I could be any of these human beings. The most common versions of the doomsday argument that I know are

A) If one assumes that population is growing, the largest number of humans will live directly before doomsday. Thus, if I am a random choice among all the humans that will ever been born, the probability is the highest that doomsday is within my lifetime.

B) I consider I am a random choice and want to know how much time is left before the end of the world. I assume a confidence of typically 95% with which I am among the last human beings that will ever been born. Since I roughly know how many people have lived before me this gives an estimate about the total number of people that will ever been born, and the time left to doomsday - with a confidence of 95%.

Okay, nice mathematical trick. Now here is what I don't understand about it.

One of the lessons from stochastic I can recall is that coincidence has no memory. Consider I flip a coin, the probability for each outcome is 1/2, and repeated flips are completely uncorrelated. I flip and it's heads. I flip again and it's heads again. I do that, say, 120 times, and the result is always the same. Then you have to make a bet on the next flip. What would you bet?

Well, okay, by now you have either fallen asleep or decided I am cheating somehow and wouldn't want to bet with me (thereby employing the Copernican principle which states that I am rather average... okay, okay, being somewhat cynical here). But let's assume this is a fair game, and I am totally unable to cheat. You'd be tempted to bet next flip does not continue this awfully unlikely series of heads, no? After all, the saying goes 'lightning never strikes twice'.

However, the probability for the next flip to show heads is (drums please) 1/2. As it was all the time. Yes, the probability for the 120 heads is a tiny (1/2)120, but the probability for the next flip is still 1/2. Coincidence has no memory. Think about Mike who enters the room after flip # 119. He sees # 120 showing heads, and the whole room goes 'ooooooh'. Mike would conclude these people are totally nuts.

Things are different if you take a bag and place in it 120 red and 120 blue marbles and pick them blindly without putting back. If you picked 120 red ones, you know the next one has to be blue. In this case, the probability depends on how many marbles you have already picked.

Now let's come back to mankind. To be clear we will state the following assumption:

1) There is a probability p that doomsday is tomorrow.

And we specify: we don't know when it is, but it's some universal property. That is to say, I am having one of my better days and I am willing to assume the presence of mankind on this planet does not increase the probability of the world ending tomorrow.

Okay. Then quantify the number of all humans that will ever been born as N and distribute them over the time prior to doomsday with function N(t), consider you are number n out of N. Take the derivative of N(t), multiply it with the speed of light, integrate it, subtract two, invert it and turn the paper upside down. Think hard about it and then tell me what is the probability that the world will end tomorrow?

Well. By assumption 1), the probability is p.

And it is in no relation with the number of people on that planet whatsoever. How come the doomsday argument suggests it is related with the number of people alive? To make the argument, the number of people living is treated as a random variable distributed over time with a probability (density), out of which you 'pick' your live span. You might picture it as a bag that contains all the CVs of all the people that will ever live, and you have to draw one. However, the way that the Copernican principle is used, there is no mentioning of how many CVs already have been distributed, so your pick has to be understood as independent of this.

This one can do for stuff like number of planets but not for events with a causal connection - like lives, or everything that has a time evolution. Even though the time evolution itself does not have to be deterministic, the total number of people at a given time is not a random variable over time. For example, if one just assumes some probability and distributes all the N people according to it, there is the small but non-vanishing probability that all the N people are born in the years 0 +/- 10 - which is impossible because it is in conflict with the evolution law for the population growth.

What one has for the population is is not a probability distribution over time, but a stochastic differential equation, that yields the probability for so-and-so many people living at a timestep t from that at timestep t-1. If one knows stochastics better than I, one can calculate a time-dependent average value for the population, around which there are random deviations, or the probability of N having a specific value at a given time. Yet, the question what is the probability of being born at a certain time is not a meaningful question to ask, because it is not independent of the times prior to that.

To come back to the two doomsday arguments.

A) Relies on the number of humans being a random variable instead of having a stochastic evolution. For an evolution law however, the Copernican principle does not make sense. Obviously, the number of people living at time t does depend on the number of people living before that. That is, you can't pick your CV out of the bag without making sure that your parents were born before you. There are causal correlations between the elements in that distribution.

B) Is a psychologically very interesting reformulation. One replaces one unknown parameter, the time when doomsday is with another unknown parameter, that is the confidence of being among the last humans that will ever live. Both parameters are related to each other. But both are still unknown. The conclusion doesn't yield any insights, it just sounds surprising.

Hmm. Running late. Have to get on that highway again. Sigh. A nice weekend to all of you :-)

Thursday, May 24, 2007

A note to all my relatives, real and virtual co-workers, friends and ex-lovers: YES! I got your emails, all of them! And yes, I am still alive, but not in the mood to type on the BlackBerry till my thumbs fall off. I am still in California, but connecting from random wireless networks causes me some security problems with the firewall back home so I'm having trouble with my inbox. You might vaguely recall that in the ancient times before email, people used a funny thing called the phone.

Anyway, despite all the running around, it is nice to be back in California. I indeed missed the people here, most of them are completely nuts, but kind of irresistibly cute. Yesterday a couple of students talked me into explaining what a center of mass is, bribing me with red-white-blue cookies. "Nah, wrong color" I said, which of course initiated a longer discussion about nationality and food color in general.

Yesterday, the hotel staff didn't know where to place my accent and, faced with my Canadian drivers licence, I was mistaken for being French Canadian. I realized that I involuntarily picked up the Canadian's funny pronunciation of 'ou' (like in 'out' or 'about')and can't get rid of it. Well, but I have also learned some new vocabulary on my trip - it's always worthwhile to talk to British guys ;-) So I found out that one doesn't sit between chairs but is caught between stools (German: Zwischen den Stühlen sitzen), and you don't have a soup and eat it, but have a cake and eat it (Die Suppe auslöffeln). Makes me wonder why German has a soup where English has a cake.

... shit... room service again... how do I get rid of them? I don't speak Spanish, and they don't speak English? GAAH, take that vacuum cleaner away, gee! Sorry, I am off for now...

Quote of the week:

"Look at all these rumorsSurroundin’ me every dayI just need some time,Some time to get awayFromFrom all these rumors,I can’t take it no more [...]"

Tuesday, May 22, 2007

In line with Backreaction's long tradition of commemorating the birthdays of famous dead scientists, today cannot pass by without mentioning Georges Remi, who was born exactly 100 years ago today, on May 22, 1907. You may wonder, who is Georges Remi, never heard of him...

Well, actually, he is not so much a scientist as a great artist. Take his initials in the inverse order, pronounce them in French, and you get Herg&eacute - the famous Belgian creator of the wonderful universe of Tintin, Snowy, and Captain Haddock.

As a kid, I loved the adventures of Tintin, and I still know by heart many details of the stories. And there is, sometimes, real physics involved: Think about what happens if you switch off the engine of the rocket that carries you to the moon (Explorers on the Moon, published in French as On a marché sur la Lune in 1952-53):

Your spaceship will be in free fall, you will be floating around weightlessly, and your whisky may leave the glass and form a perfect amber-coloured sphere. That's exactly what happens to the fearless explorers half-way to the moon:

As I can see from the previous post, my husband has very pauciloquently apologized for my absence. I am presently in LA, and I can report proudly that I am making progress getting lost in the City of Angels (I keep thinking Lost Angeles might be more appropriate). The only reliable statement about the Highway 405 I can make is that my exit is always the one that is closed. This time, it's Venice Blvd. which is little more than a construction area. Amazingly, despite the fact that I've lived in California for a year, the sight of a street sign saying '101 HOLLYWOOD' still makes me smile.

I have given the hotel in Venice Beach a second chance. This time I actually met the manager who turned out to be like 16 years or so. (And if he isn't, then I'd really like to have the number of his plastic surgeon.) The wireless is constantly dysfunctional, which might have something to do with the electricity being of a certain 3rd world quality with lights flickering each time the fridge turns on. But anyway, I found besides the hotel's wireless there's another wireless here, very creatively named 'venice'. It's secured, but amazingly my first try for the passkey was accepted (have a guess).

But now to the really interesting part. I've finally met Clifford from Asymptotia, who spent his Sunday taking me on what he called 'The Asymptotia Tour', showing me the nicer places in LA, and, definitly the mayor should pay him for that :-) Clifford turned out to be an entertaining tourist guide, with a cute British accent and a cool hat. Here he is, hat included:

Friday, May 18, 2007

For a 3-D view of the yard without the duck see here. If you load the file, she's sitting underneath the tree behind you, the one not on the lawn but in the middle of the terrace (the tree hasn't noticeably grown since the picture was taken.)

Of course the smart duck has chosen one of the world's excellence centers in theoretical physics because of the intelligent conversation by all the Potentially Ingenious smokers hanging around there.

Okay, okay, maybe it was just the ground color. Look how perfectly she fits in there. (In fact it seems, most people have missed her even though she's sitting directly opposite the door and between two tables.) Too bad I will be away the next weeks.

Thursday, May 17, 2007

I just got a phone call from LA. The hotel guy confirming my reservation. It gave me the opportunity for my line of the week: "Sorry I missed your call, I was in a press conference with the prime minister." Silence. "Pardon?" - "Well, I mean the government supports the Institute with 50 Mio $, that's a reason for a press conference, eh?"

As I've mentioned in an earlier post, Canada is great and the present government "provides $50 million to the Perimeter Institute in 2006–07 to support its leading research, education and public outreach activities". So today there is the press conference to make sure the media has a chance to appropriately appreciate the investment in research and development.

Sounds good, but is actually pretty annoying. Starts with me being unable to find a parking spot, I had to park on the museum lot next door, which has a 2 hour limit.

The lobby is crowded with suits in black and blue, and it takes me some while to locate the secretary who has a package for me at the reception. (Turns out to be the SUSY '06 proceedings.) The press conference is scheduled for 11:40 am. We researchers were asked to please sit in the back. The auditorium is full with cameras. The Mr. Importants arrive appropriately late at exactly noon. On the photo below from left to right: Mike Lazaridis also known as He-Who-Started-It-All or Mr. BlackBerry; then there's the Canadian prime minister Stephen Harper; in the middle the person with the crumpled suit and sloppily knotted tie is our Director Howard Burton; then there's another minister, and another minister. I think it was the minister for Industry and the one for Finances. Or the other way round. Sorry for the bad photo quality. And sorry, being an ignorant immigrant, I have no idea who these ministers are.

They all said a lot of nice words that are too big to fit into this blog. To make a long story short, science and technology is important for Canada's future, funding research and development is essential for innovation and national competitiveness, and "Canada promotes World Class Excellence" (i.e. PI). As the information brochure Mobilizing Science and Technology says "The Government of Canada will ensure that its policies and programs inspire and assist Canadians to perform at world-class level of scientific and technological excellence". Wow. I am tempted to send this brochure to Angie. But seriously, sitting in the back of the large lecture hall with flash lights flickering, I felt the urge to thank Mike for making PI possible. I have been at quite a number of Institutes but PI is without doubt in several regards exceptional.

Anyway, if you want to see motion in research, the easiest way to mobilize scientists still is just a good buffet.

Now I've got to go move my car. I hope all the TV vans are gone by now.

Tuesday, May 15, 2007

My secretary prints it, brings it with the morning coffee, and I dictate an answer by 5pm.

If your email doesn't end on dot edu you can still be lucky and get an out of office reply.

If I don't answer within one day, your email drops out of the front page and you can forget about it.

I take my BlackBerry with me to the bathroom and can answer one-handed while holding the paper in the other hand.

According to a survey by the Center for the Digital Future in Los Angeles, more and more Internet users believe that e-mails should be answered in a short time span. In 2006, 23.8% said emails should be answered as soon as possible (up from 21.3%) and 34.6% said within one day is fine (up from 32%). Two out of a thousand find it not necessary to reply at all. Interestingly, it's totally okay to answer an email within a week, but completely unacceptable to answer within 4-5 days.

Gee, now I am stuck in my office! Jimmy (my office-mate) just concluded we'll have to stay over night (fortunately there are plenty of couches at PI). I don't think I've ever seen a thunderstorm like this. It's suddenly gotten dark, even the street lights turned on. I thought I might have forgotten there's an eclipse of the sun. Winds came up. The tree directly in front of my window lost every branch smaller than my arm within 5 minutes. The water is about to be blown out of the lake. Now it's raining so heavily I can't even see that stupid tree. In the distance I hear an ambulance. It's kind of scary, and I just realized I forgot to close the windows at home...

Update, 30 minutes later: Sun is shining again, and we have a beautiful rainbow...

Monday, May 14, 2007

Frankfurt is the only city in Germany with skyscrapers, and a skyline. Seen from a distance, it could be somewhere in North America. After the river Main that goes through the city, Frankfurt downtown is commonly called 'Mainhattan'.

If you are walking around in town, and do not happen to work in one of these bank towers, you can only look up to the buildings - there is only one of them, the Main Tower, which has a viewing terrace on the roof and is accessible for everyone.

This weekend, everything was different: It was the 'Wolkenkratzerfestival', the Skyscraper Festival, and you had a chance to visit and ascend most of towers. Well, you could have, if you had been lucky and obtained one of the 80.000 or so tickets that were distributed for free via a webpage two months ago. It seems that all tickets were gone within an hour or two.

For all those people who, like me, didn't have that luck, there was a big party organized in town, and the day ended with an impressive firework. That was again looking up to the towers - but great!

Sunday, May 13, 2007

The other day I was grocery shopping and, being in a weekend mood, I dropped some of the soft science magazines into the cart. At the register, the guy in front of me (two glasses mixed pickles and a sixpack Canada dry) made a funny face."You readin that?", he asked and pointed to a headline about Cannibal Galaxies!, "Ain't no readin for a pretty girl like you." My turn to make a funny face then. In a rather unsuccessful attempt to imitate his accent I said "What's the right readin then for me? - Playgirl?"

Mr. Mixed Pickles considered whether to be insulted or amused, looked at the tampons I threw on the register and decided on apologizing. "Sorry, Miss, just thinking." While I tried to figure out exactly what he might have been thinking, he added "You know, if you interested in that stuff, there's these people at the institute down on Bridgeport, they do all kinds of weird things there." Yes, I think. Right, all kinds of weird things.

Later I sat at Starbucks on King Street, scribbling notes on a pad, sketching a talk and trying to decide which equations to put on the slides. Somebody accidentally bumped into my chair, and I drew a long line across the paper. A blond man, maybe mid fourties, very pinkish face. Formal shirt, no tie, uppermost buttons opened. He looked at my notepad: "Whats THAT?!", sweat on his forehead. "Propagator", I mumble, "Gauge field. Momentum space." The sweaty forehead frowned at me. "Physics", I said. "Ah! Physics! Are you doing that for money?" - "No." I said. What was I thinking? You tell me.

He looked at me like I was an unsolved equation, then he saw my pen, Perimeter Institute printed on it. "You ARE doing that for money!" he concluded, triumphantly, much as my office mate when he's found that extra minus which got missing.

I had not much desire to speak to him, an aura that I know how to radiate very efficiently, so he nodded a good-bye. While vanishing in the back of the room he said "Very special place that institute."

Yesterday, I am at Starbucks again, sitting outside on what I am convinced is an IKEA table, when he comes by. He grins at me and my book, "Madame Curie!" he says, and tips an imaginary hat.

Saturday, May 12, 2007

Yesterday evening, the 2nd 'Decoherence Night' at PI took place. This time we had a live performance in the new building's Black Hole bistro. Here we have multi-talented Federico Piazza playing the guitar and the harmonica:

Friday, May 11, 2007

I have a lot of prejudices. Most are about academics. One such prejudice is that the average academic either is a Jazz-fan or an aggressive defender of classical music, but no way he would admit on listening to *gulp* mainstream music (independent thinking and all). Interestingly, if you plug in your laptop to the PI network and have iTunes installed, it wants to share your files with other computers in the network. For example with mine. In such a way, I have heard quite a lot of interesting music. From Chinese techno, over Italian guitar music to completely unidentifiable rather weird electronic loops. The obvious Jazz-stuff of course. And an astonishingly high amount of Avril Lavigne and Christina Aguilera.

Anyway, it seems already the presence of the two letters Dr in front of my name leads people to accuse me of living in an ivory tower, and of not knowing what 'real' life is. This is of course completely correct, since I am not 'really' living. Occasionally, I am reminded of this. For example, I talked to a friend on the phone recently and was extensively complaining about the referee process of one of my papers, going on forever about peer review and editors who don't know a fermion from a boson. Until my friend interrupted me rather annoyed to tell me she has no idea what I am talking about, and would I please recall not everybody publishes papers in scientific journals. Okay. Now I am back to earth. Since the header of this blog says something about every day blahblah physicists, here's how to publish a scientific paper.

1) Have something worth publishing. For inspiration, see e.g. my Paper Recipe , or read some of the weirder comments on this blog.

2) Pick a journal. Not an easy task. There are a large number of scientific journals in various degrees of specialization. The broader the context of the journal, the larger the audience that you can reach, but the harder it will be to get published. A more specified journal is generally more supportive in the refereeing process. If you chose a leading and highly cited journal, be prepared for rejection. I believe for example PRL receives much more papers than they can possibly publish, so the rejection quote is somewhere around 70%, not to mention Science and Nature.

3) Find out the specifics of the journal. What is the main scope? How much details are appropriate? Is there a page limit? If the journal publishes several kinds of papers, which form is the most suitable for your paper? A note, a letter, a full research article? If possible, download a sample file.

4) Write the paper. This is the difficult task. To begin with, your paper should actually have content. It should be a new result, and you should appropriately embed it into the existing research. Keep in mind what audience you are writing to, and make sure to meet the standard of the journal.

5) Okay, lets just assume you have mastered that. Now you submit your stuff to the journal. In most cases you do that today via an online form (e.g. the one at Physical Review D). You then get a reply that acknowledges receipt of the manuscript and reminds you of the rules of good scientific publishing. Looks somewhat like this:

Dear Dr. Hossenfelder,

The editors acknowledge receipt of this manuscript on xx/yy/zzzz and are considering it as [type of article] in [journal].

We understand your submission of this manuscript to certify the following:

- The paper represents original work of the listed authors.

- The manuscript as presented accurately reflects the scientific results.

- All of the authors made significant contributions to the concept, design, execution, or interpretation of the research study.

- All those who made significant contributions were offered the opportunity to be listed as authors.

- All of the listed authors are aware of and agree to the submission of this manuscript.

- The manuscript has not been published, and is not now and will not be under consideration by another journal while it is considered here.

- As part of the submission, the authors have provided any relevant information to the editors (e.g., information about recent relevant unpublished manuscripts by the authors).

- The authors accept the established procedures for selecting manuscripts for publication.

In most cases, your paper will then be assigned to an editor who knows the field you are working in.

6) Now you wait for the editor of the journal to pick one or two of your colleagues to read and report on the paper. This is the dreaded peer review process. This stage can last arbitrarily long, depending on how often the referee has to be reminded of his task, how long it takes him to decline, or the editor to give up on it and chose somebody else. For my papers, it usually takes between 4 weeks and 4 months.

7) Eventually, the editor will send you the referee's report. Some journals indeed only ask for one report (imho not a good procedure). However, in one case I have received four reports (they all said the same but the editor still didn't know whether that was good or bad). Referees are usually asked to classify the paper into categories ranking from

I agree with the referee that your manuscript is not acceptable for [the journal]. Please do not resubmit it or submit other papers to [the journal]. I will not be able to acknowledge [sic] further submissions.

If you are rejected in the first round, don't bother resubmitting. In my experience it's a lost case, even if you could prove that the referee didn't read the paper at all. However, usually the rejection has a good reason and you should carefully think about it. There are many things one can criticise about the peer review process (e.g. the importance of your home institution or your previous publications), but in most cases it works - somehow.

The most likely thing to happen is a report that raises several more or less fatal points, and you are asked to review your paper. Even in case the referee has no point, you will usually be asked to do SOMETHING. Like, changing the title, or exchanging section IIa with IVb, or to 'improve grammar and spelling'.

8) Assumed that you can address the referee's concerns, rewrite your paper, and resubmit. It goes back to the editor, and to the referee. Who will hopefully read it, and write another report: this is the important one. At this stage, most papers get eventually rejected. However, in principle this back and forth with the referee can go on forever, easily more than a year. In many cases I have to say the exchange with the referee has taught me a lot. Even if the paper was eventually rejected. In at least as many cases however, the referee reports were as annoying as ridiculous. A very common practice is e.g. that the referee will 'suggest' you cite various papers of 'some person' (guess who).

9) If everything works out, you will eventually get a message saying: We are pleased to tell you that your paper has been accepted for publication... Go, celebrate! If you haven't already done so with the submission, you will now be asked to sign a copyright form. (In most cases you can now do this online.)

10) Some while after that you will receive the proofs of you paper, that is the final layout of the manuscript how it will be available on the journal sites (and if a print journal be printed). You will most likely be asked to answer some queries, and update your reference list.

Never submit your paper to several journals at the same time. It can result in serious copyright problems.

Don't complain about the referee to the editor. It doesn't help anything. If you have concerns about being refereed by a competing colleague, mention this with the submission before you get assigned to a referee.

In most cases, the editor will chose authors of a paper you have cited as referees, you should keep that in mind.

Never reply to a referee report immediately. Especially not if you are upset. Breathe deeply, sleep over it. Keep your answers polite, no matter what.

If you resubmit a revised version, make sure it does at least look different, and that you included all references the referee 'suggested'.

Read the proofs carefully. In many cases mistakes appear in this version, ranking from messed up integrals to unfortunate line breaks in equations, or even the use of completely wrong symbols (in my last paper all \hbar's suddenly became \bar h).

Tuesday, May 08, 2007

As you might know, I am interested in the possibility to experimentally test quantum gravity. The big obstacle on the way to doing so is that the effects are extremely small, because gravity is so weak. It might not seem all that weak to you, gravity being what holds you down to your chair right now, but the only reason why we observe it at all is that gravity - unlike all of the other interactions - can not be neutralized, and so it adds up. But if you think about it, if you pin a magnet to your fridge, that tiny magnet's force is sufficient to act against the gravitational pull of the whole earth.

If one estimates as an example the ratio between the electric and the gravitational force between two electrons one finds [1]

Where mpl is the so-called Planck-mass and related to the gravitational constant as 1/mpl2 = G. That is, the gravitational interaction in this case is by roughly 43 orders of magnitude smaller than the electric one. The reason for this is that the mass-scale associated with gravity, the Planck-mass, is much much larger than the typical particle masses. Nobody knows why that is, this is also called the 'Hierarchy problem'. On the other hand, macroscopically seen the Planck-mass isn't a large mass at all. In fact, it is a scale that is perfectly handy for experiments. In grams, the Planck-mass is roughly 22 micrograms.

Last year, I came across a paper by Dr. Raymond Chiao who proposes an experiment to exploit this fact

Naturally, I was very interested and looked into the topic. Since there were many details I didn't understand, I have been in email contact with the author for some while. Three months ago, there was a newer, and more extended version on the arxiv: gr-qc/0702100, which caused me to again contact Dr. Chiao. In the following I would like to share my concerns about the effect explained in these works.

The proposal is to use objects of about Planck-mass that only carry a total electric charge of order one. For these objects, the electric and gravitational force would then be of roughly the same strength. The concrete scenario which Chiao describes uses something called 'Millikan Oil Drops'. I admit that I don't understand all the features of these drops, but essentially these are cooled and super-fluid helium drops coated with electrons. Their superconductivity is claimed to be an important part of the experimental setup.

These drops, so the claim, would be strongly coupled to gravitational radiation, and could amplify it such that it becomes detectable [2]. Essentially you can envision a pair of drops acting like an antenna. Excited through a periodic electromagnetic field, they would emit both electromagnetic and gravitational radiation. It is argued that gravitational radiation has to be as strong as the electric radiation, because the droplets are designed such that they are equally strong subject to both forces: "This is a strong hint that mesoscopic-scale quantum effects can lead to non-negligible couplings between gravity and electromagnetism that can be observed in the laboratory."

The first obvious objection that springs into my mind is, yes, both forces act equally. But equally weak. There is no way the process of simply cooling matter can affect the gravitational force, unless one introduces some kind of modification of gravity. But Chiao claims this is an effect of purely classical general relativity, and there is no modification necessary. I was looking for a derivation of the gravitational wave emission. There is none, in neither work. All that one can find is the electromagnetic case, and then the repeated argument that the gravitational case is identical. In such a way, Chiao derives the drops are reflecting gravitational waves: "Hence it follows that nearly perfect reflection of gravity waves should occur from a superconductor at temperatures well below its transition temperature."

This argument can very easily be defeated. The electric charge of the drop is confined to the surface (they are 'coated'). The mass of the objects is equally distributed throughout the drop. Thus, the source terms for both, electromagnetic and gravitational field are not equal. The argument that both can be treated by applying a symmetry principle just does not apply. Though in a linear approximation of gravity both are essentially described by a wave-equation, both have different initial values. The paper says: "From the Maxwell-like equations [...], and the boundary conditions that follow from them, it follows that there should exist an analogous reflection of a gravitational plane wave from a planar vacuum-superconductor [...]". The boundary conditions hardly ever follow from the equations.

I also totally don't understand why one could possibly expect superconductivity to enhance classical gravitational effects. The argument relies on a postulated symmetry between gravitational and electromagnetic behavior. Even if one believes it, this symmetry would be based on the low temperature and the amazing properties of the droplets. Yet, the gravitational field of the droplets doesn't change with the temperature. How then can such an experiment possibly change the behavior for gravitational waves? I do understand that the electromagnetic properties change, but I find it extremely implausible to conclude from that that the gravitational field is also affected [3].

Since the effect can not be caused by the electric properties of the electrons, it had to be caused by their motion. It could then only be the masses of the electrons that cause the gravitational radiation to be strong. But this is more than implausible. The whole setup takes place in the linear regime of gravity. The total mass of all of the electrons is many orders of magnitude lower than the total mass of the droplets. A contribution to the gravitational field that is several orders of magnitude smaller can in the linear regime not result in a radiation that is several orders of magnitude larger (than that of the object without the electrons).

There has been some experimental evidence that superconducting materials might display unusual gravitational effects. I am somewhat sceptical about that, but it might be possible. Who knows? That is, the proposed experiment might be worthwhile to do. However, whether or not there is such an effect, I have very strong doubts about the explanation offered in Dr. Chiao's papers.

Aside: I would have liked to share here part of my email communication with Dr. Chiao to make sure I did not misinterpret his explanations, but he didn't agree on that [4].

Footnote 1: The speed of light and Planck's constant are equal to one, so are maybe occurring factors of some pi or 137 or so.

Footnote 2: One should note here that gravitational radiation has never been directly detected. Indirect detection through radiative loss in binary systems was awarded with the Nobel Prize in 1993.Footnote 3: Strictly spoken, the gravitational field of course is affected if the electromagnetic field changes since the electromagnetic field strength also is a source to the field equations. However, compared to the mass of the objects this is a negligible effect. It neither affect the conclusion, nor is it claimed by Chiao to be responsible for the effect.

“Insanity: doing the same thing over and over again and expecting different results.”

~Albert Einstein

"In truth, it's not easy to predict who will turn out to be a visionary and who a crank, says psychologist Angela Duckworth of the University of Pennsylvania, who studies the traits that lead to success. Geniuses and catastrophic failures share many of the same characteristics, including determination, intense concentration, passion, and a disregard for conventional wisdom. "And both are willing to persist when everyone else thinks it's a ridiculously low-probability idea," she adds."

Saturday, May 05, 2007

If I am bored, I like to read Wikipedia entries about people I know. This is always very amusing. I wonder how long it will take some of the the contributors to realize that the attempt to capture more than CV facts about 'living people' in an 'encyclopedia' is doomed to fail. Better wait until they are dead so you can analyze them ad infinitum. At least they then won't change their mind anymore, isn't that an annoying habit?

Something else that always gives me the giggles is Googling my own name. One can find a number of really interesting statements about me. My favourite is definitely this one:

Well, Real Steve, indeed. There's nobody more serious than me when it comes to pillows, though occasionally I know better things to do than talking. Woo Hoo.

My bike has made it on a blog called 'American at Heart', and Marcus' guess at physicsforums that I drive a red Miata is already a classic. (I am still driving a Honda, though the color has changed from white to black.) My Inspiration has made it into Spanish (so I assume. Even though I receive my bank statements in Spanish, I don't speak it), and the Wildwestsound made it into a livejournal called 'there is no spoon' (I too would go for the red pill) accompanying a fictitious dialogue of the kind

"Duff: He's lying guys, just listen to the two-faced bastard...[...] You see, he's a string theory denier and just won't admit it! Not only that, but he's a pompous ass!Smolin: That was the wrong version of my book, dumbass. "

Somebody would be very disappointed to find out how polite physicists are in reality, but then if there is no spoon, what is reality anyway? But, hey: Wikipedia knows!

The invited talk about QG phenomenology at LOOPS '07 will be given by Sabine Hossenfelder, it is her specialty. She is the person who could best give the overview to answer your question about "when will..." [QG be tested] click on http://www.matmor.unam.mx/eventos/loops07/index.html again and on PROGRAM and scan down to Hossenfelder [...]

She will sound pessimistic but that is normal for phenomenologists---they are supposed to be unenthusiastic, uncommitted, cautious, and a bit of the devil advocate who throws the cold water of reality on the theorists. But hers is the talk you should hear if you could be there, if you ask those phenomenology questions relating to testability.

This is quite remarkable because I am not even yet sure what I will be talking about (forget about the abstract, I haven't changed it for some years, it says basically nothing). I wasn't aware that being a phenomenologist would require me to be unenthusiastic and uncommitted. If that's what you expect from me, I am afraid you'll be awfully disappointed. In fact, I am usually extremely optimistic.

But I guess some of my colleagues would say I am pretty good with the cold water trick. I can't even recall how many nice ideas I have killed in my life (a considerable part of which were my own.) Indeed, I seem to be very talented in finding flaws. I believe this is due to a combination of being German and a teacher's daughter. My most recent achievement was debunking Dr. H's theory that the fish in the lake next to PI jump because they are gasping for air.

Maybe somehow related to the above or maybe not: If you want to have a laugh, have a look at the deleted nonsensical entries at Wikipedia. You find an excessive list of these under 'Bad Jokes and Other Deleted Nonsense'. My favourite is

"The banana.....possible one of the most cunning and elusive fruits in our world. The banana is also one of the smartest fruits on the market, having a great knowledge in algebra and american history, it is been lead to belive that the banana may to be too smart for our time. The reason we mass grow and eat banana's is so that they cannot group up in large numbers and form a revolution, overthrowing our government and sending our society as we know it into turmoil. The banana has been traced back to the cause of many species becoming extinct. Many predators try to attack the banana thinking it is only an inatimate object.Once the predator comes close enough, the banana has been known to use it's skills in ninjitsu and quick the animal with one swift blow to the head."

And interestingly, Canada seems to be a frequent target of Wiki-vandalism. Here is one:

Vandalism to CanadaAt 18:54, 19 July 2006, 66.220.104.149replaced the article "Canada" with this:-------------------------------------------"Canada, also known as America's Hat, Soviet Canuckistan, or The Shizzle North of Hizzle, but more commonly known as the Great White North, is situated somewhere near the inconsequential continental U.S.A., and slightly south of the North Pole. The United Nations has managed to narrow it down further to not only north of the U.S. but also up, eh? To answer the question the entire world is asking, yes, Canada has an Army, and no, Canada doesn't know about it.

Canadians are known for their peacefulness and politeness in distressing situations, such as during a war or hockey playoffs. The world looks to Canada for international peace-keepers, since they possess no weapons other than snow shovels, and their jovial accent and flannel clothing are comforting. The unanimously[5] agreed upon capital of Canada is Toronto, although a small number of government offices are located in the far less important city of Ottawa. Proposals made entirely and only by Torontonians have been made to move said offices to Toronto, but have yet to be approved. The city has considered separating from the country because of this. The rest of Canada, meanwhile, continues to think that Toronto "blows" and that the city's curling team, the Leafs, "suck". The world sees Canada as America's dorky half brother. Canada and the USA share a common mother, that being England, but while America's father was apparently Jesus, Canada's was France. While little brother Canada may not be able to throw the ball as far as its "cool" older half-brother America, Canada can at least find itself on a map (of course, Canada finds itself by locating the USA and going north, much like Mexicans find America by locating Mexico and going north)."

Friday, May 04, 2007

"Is this some kind of slum, or what are these little shacks at the outskirts of Frankfurt? Are people living there?"

That's what an American postdoc asked Stefan last week when discussing the best way to ride from downtown Frankfurt to the physics institute by bicycle. Along this route one passes many of these colonies.

During summertime some people may actually live there, but these huts and gardens are definitely not slums. They are allotment gardens, also Kleingärten (small gardens), or Schrebergärten, as they are called in German, after physician and social reformer Daniel Schreber.

The institution of these gardens goes back to the time of industrialisation. They were meant to improve the health of the working class in the expanding cities, and to allow them to grow their own food. The small gardens are now very typical for German cities, especially in crowded areas where many people live in apartment buildings, and where there is too little space for growing the own Marijuana potato supply.

Also Einstein had one when he lived in Berlin: It was in the "Kolonie Boxfelde" in Berlin-Spandau. He spent the summer of 1922 with his sons in the hut in the garden, which he called his "Spandau Castle". (It seems he was quite happy that his wife Else didn't like too much to stay there.)

But there is a caveat to the idyll of the garden... Most of these garden's colonies are subject to some kind of, well, group think. You know, they form their own sub-community and want everything to be clean and nice and pretty looking (Germans call that "Vereinsmeierei").

If one disturbs the good German cleanliness, say, by forgetting to water the plants while being busy with explaining the universe, or is just too lazy to remove the weeds while throwing dices with God, one will get in touch with the authorities soon. That's was happened to Einstein on September 12, 1922:

Bezirksamt Spandau to "Herr Professor Einstein": You are presently leasing allotment 2 at the Burgunderweg in Boxfelde. Said allotment has not been managed since a long time, weeds have spread all over the whole parcel and have soared. The fence is not in order, and the whole allotment makes an unesthetic impression. We have to assume that you are no longer interested in leasing the parcel, and we will give it away to someone else, unless you object prior to the 25th of this month, and the allotment is put in order until that date. Please take care of the removal of this nuisance, and give us further notice.

This letter is even more typical German than the gardens themselves.

By the way, Einstein kept the deadline, but the Spandau Castle was never mentioned after this.

Wednesday, May 02, 2007

Maikäfer Flieg is an old German nursery rhyme - you can listen to the tune as midi file. The text is very dark, it translates to

Cockchafer fly,father is at war,mother is in Pomerania,Pomerania has burned down,Cockchafer fly.

and is thought to go back to the times of the 30 Years' War, when large parts of Germany were completely devastated and Pomerania, then associated with Poland, lost two thirds of its population. No idea why the cockchafer, or maybug, is associated with this misery.

The maybug feeds mainly on broad-leafed trees, and its larvae, the chafer grubs, especially like the roots of trees. The larvae develop in the ground for the long time span of three to five years, and the bugs work their way to the surface around end of April, beginning of May. The bugs parading in the photos were attracted by the light in the kitchen of Stefan's mother last Saturday night.

The long development period favours the occurrence of the maybugs in cycles, and so, they can be quite a nuisance to forestry and agriculture. Massive use of pesticides had the consequence that they became very rare in the 1970s/80s. But this year, there seem to be again quite a lot of them around - Maikäfer flieg!

"Relativity is just science's way of flip-flopping. Space or time, mass or energy? Which is it, pick a side [...] And I'm sorry, E equals m c squared? C does not stand for the speed of light, c is for cookie."

I makes me really happy to see that scientific ignorance is no longer en vogue. I just want to fill you in with the details that Colbert skipped in his brief introduction. First, as everybody knows the relevant factor between the cookie that he talked about and the entertainment is the media

Tuesday, May 01, 2007

"They have a reputation for being big-headed, but New Yorkers showed they are big-hearted, too, by finishing first in our global courtesy ratings. They placed in the top five in all three tests and were particularly polite when it came to holding doors open, with only two people failing to do so."

Second is Zurich, followed by Toronto, Berlin and Sao Paulo. The criteria for the ranking were based on these three tests:

1) walking into public buildings 20 times behind people to see if they would hold the door open

2) buying small items from 20 stores and recording whether the sales assistants said thank you

3) dropping a folder full of papers in 20 busy locations to see if anyone would help pick them up

I am about to drop a folder full of papers on the corridor and see what's going to happen.